Projectsummary KeygoalssetforthbytheNationalHIV/AIDSStrategyaretoreducedisparitiesinengagementinHIVcareand HIV-relatedoutcomes. BlackpeoplewhoinjectdrugshaveamongthelowestratesofretentioninHIVcareand viralsuppression,andthisrealityduringthecurrenteraofeffectiveHIVtherapysuggestsadditionalstrategies areneededtoeliminatebarrierstoachievingtheseoutcomesamongthispopulation.Well-documented barrierstoretentioninHIVcareandviralsuppressionincludelowincomestatus,homelessnessand incarceration.Theseindividual-levelbarriersdonotdevelopindependentofcontextualfactors,including featuresofneighborhoodswherepeoplereside,however.Thegoaloftheproposedstudyistoidentifynew targetsformultilevelHIVcareandtreatmentinterventionsforBlackpeoplewhoinjectdrugsbydeterminingthe temporalimpactofpreviouslyunexploredneighborhoodfeaturesonretentioninHIVcareandviralsuppression amongBlackpeoplewhoinjectdrugs,andidentifyingpotentialhealthcare?resiliencefactors?thatoffset negativeimpactsofexposurestohazardousneighborhoodfeatures,includingthoselessmalleabletochange. Wewillcombinedatafromthelongest-runningcohortofHIV-infectedBlackpeoplewhohavehistoriesof injectingdrugsinBaltimore,Maryland(TheAIDSLinkedtotheIntraVenousExperienceStudy)infollow-upfor twodecades(1997-2017)withadministrativedataonneighborhood-levelfeatures,andwillutilizerigorous marginalstructuralmodelingtoaccomplishthefollowingaims:Aims1and2:Assesslongitudinalimpactsof exposuretoneighborhoodfeatures(e.g.,neighborhooddrugmarketactivity,spatialaccesstodrugtreatment andsyringeexchangeprograms,housingaffordability,gentrification,etc.)measuredatasinglepointintime andcumulativelyonlapsesinHIVcareandvirologicfailureamongHIV-infectedBlackpeoplewhoinjectdrugs inBaltimore,Maryland.Sub-Aims1and2:Explorewhetherhealthcarefactors(e.g.,consistentandtrustworthy HIVcareprovider)modifytheimpactof?point-in-time?andcumulativeexposurestoneighborhoodfeatureson subsequentlapsesinHIVcareandvirologicfailureamongHIV-infectedBlackpeoplewhoinjectdrugsin Baltimore,Maryland.Theproposedstudywilladvancenationalprioritiesbyinformingthedevelopmentofan interventionthatconnectsHIV-infectedpeoplewhoinjectdrugstocommunity-basedprogramsandsocial servicesbasedonresidentialhistoryandexistingsocialcapitalwithinhealthcaresystems.